Fans were quick to comment on Williamson's photos, with many noting that Simmons was probably hitting the gym hard for his role as Commissioner Gordon in the upcoming fantasy film, Justice League, which also stars Amber Heard, Jason Momoa, Henry Cavill, Ben Affleck and Amy Adams.

Others joked that seeing these pics was enough motivation to start getting serious about their own diet and fitness plans.

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JK Simmons is 61 and super jacked -- see the pics!

HOLLYWOOD, CA - JUNE 05: Actor J.K. Simmons attends the premiere of 'Worlds Apart' at the 2016 LA Greek Film Festival at the Egyptian Theatre on June 5, 2016 in Hollywood, California. (Photo by Paul Archuleta/FilmMagic)

HOLLYWOOD, CA - FEBRUARY 28: Actress Alicia Vikander (R), winner of the Best Actress in a Supporting Role award for 'The Danish Girl,' poses with actor J.K. Simmons in the press room during the 88th Annual Academy Awards at Loews Hollywood Hotel on February 28, 2016 in Hollywood, California. (Photo by C Flanigan/FilmMagic)

NEW YORK, NY - JANUARY 08: Actor J.K. Simmons appears on Opie Radio at SiriusXM Studios on January 8, 2016 in New York City. (Photo by Michael Loccisano/Getty Images)

NEW YORK, NY - JANUARY 07: Actor J.K. Simmons attends the AOL BUILD Series to discuss his new film 'Kung Fu Panda 3' at AOL Studios In New York on January 7, 2016 in New York City. (Photo by Mike Pont/WireImage)

NEW YORK, NY - JANUARY 07: Actor J.K. Simmons attends the AOL BUILD Series to discuss his new film 'Kung Fu Panda 3' at AOL Studios In New York on January 7, 2016 in New York City. (Photo by Mike Pont/WireImage)

LOS ANGELES, CA - SEPTEMBER 24: Actor J.K. Simmons attends the Sunshine Kids Foundation and LAPD host Young Cancer Patients with cast at the 'Major Crimes' set at Raleigh Studios on September 24, 2015 in Los Angeles, California. (Photo by Lilly Lawrence/WireImage)

TORONTO, ON - SEPTEMBER 14: J.K. Simmons arrives at 'The Meddler' premiere during the 2015 Toronto International Film Festival held at Princess of Wales Theatre on September 14, 2015 in Toronto, Canada. (Photo by Michael Tran/Getty Images)

J.K. Simmons during Landmark Club Restaurant Opening & Richard Belzer's Birthday Party - September 23, 2000 at Landmark Club Restaurant in New York City, New York, United States. (Photo by Ron Galella/WireImage)

J.K. Simmons & wife Michelle during 'Spider-Man' Premiere at Mann Village in Westwood, California, United States. (Photo by SGranitz/WireImage)

JK Simmons and William H. Macy during Fox Searchlight Pictures presents the Los Angeles Premiere of 'Thank You For Smoking' at DGA in Hollywood, CA, United States. (Photo by E. Charbonneau/WireImage for Fox Searchlight Pictures)

Charles Barkley and J.K. Simmons 11064_537.JPG during 2006/2007 TBS and TNT Upfront - After Party at Madison Square Garden in New York City, New York, United States. (Photo by Theo Wargo/WireImage)

Actor J.K. Simmons arrives to the premiere of 'Rendition' at the Academy of Motion Pictures Arts and Sciences on October 10, 2007 in Los Angeles, California. (Photo by Steve Granitz/WireImage)

The legendary role was most recently played by Gary Oldman, and the 58-year-old actor couldn't be happier with Simmons' casting. When ET chatted with Oldman at a press junket for Criminal, he revealed he was "absolutely happy" to hear about Simmons taking on the character.